To change the text in the catalog, you want to go to CatalogPageComposer.cs and find frontpage4
The images can be found in your c_images. The page link is the page you want to go when it's clicked. To find out a pages link go to catalog_pages table in database, find the page you want and then look at the page_link column value.
For your second point, you want to edit server_landing in the database.